Swab cup



1968 H. E. BOWERMAN 3,417,673

SWAB CUP Filed Aug. 1, 1966 Wank Fig.5

PRIOR ART Fig. 6

ART

' INVENTOR ZORA MAE BOWERMAN EXECUTRIX OF H 3@ Fig] ULIE E BOWERMAN ATTORNEY? United States Patent 3,417,673 SWAB CUP Hulie E. Bowerman, deceased, late of Tarrant County,

Tex., by Zora Mae Bowerman, executrix, Tarrant County, Tex., assignor to Oil States Rubber Co., a

corporation of Texas Filed Aug. 1, 1966, Ser. No. 569,527 4 Claims. (Cl. 92-241) ABSTRACT OF THE DISCLOSURE A resilient swab cup body having a rigid base and having reinforcing wires embedded axially in the periphery of the cup and pivotally captivated in the base, and reinforcing means to uniformly distribute loading pressures in the lower end of the cup body and to control the degree of extrusion of the body material downwardly and outwardly between the lower ends of the Wires, the reinforcing means comprising a rigid cup-shaped ring member embedded in the body just above the base and opposite the lower ends of the wires, the ring being displaceable toward the base to thereby flow a controlled amount of base material toward and between the wires before the ring contacts the base.

This invention relates to improvements in well swab cups, and particularly in the type of cup employing reinforcement of the cup elastomer by wires extending axially of the cup and secured in a metal base.

An object of the invention is to provide a reinforced swab cup which will function properly under a wider range of fluid loading conditions than has previously been possible with conventional cups of the type shown in my Patent 2,862,776, wherein the reinforcing elements are captivated at their lower ends in the flange of a metal base in order to secure the lower ends against dislodgment, but wherein the upper ends of the Wire elements are allowed radial movement to insure the best possible sealing the cup against the well pipe to provide optimum swabbing action, as is well known in the prior art.

More specifically, it is the object of this invention to improve the load carrying capability and the life of a cup of the above type by inserting an additional reinforcing ring into the elastomeric portion of the cup just inside of the wire reinforcements and just above their lower ends but out of contact therewith, this novel ring being advantageously shaped to prevent or limit the downward and outward flow of the elastomer between the reinforcing wires, as occurs when a conventional swab cup is heavily loaded and is slumping. Such outflow of elastomer leads to pinching of the flowed material between the swab and the wall of the pipe and to chewing off of the pinched material in a manner well known to those skilled in the art. Various expedients have been used to try to avoid this loss of elastomer, mostly comprising sleeves of harder material disposed outside and around the lower periphery of the cup, but the present ring is believed to be an improvement, both functionally and from the point of view of protecting the added ring from deterioration by corrosion, the ring being embedded within and bonded to the elastomer.

An advantage of the present ring, which is preferably separate from and spaced above the metal base, is that when the cup is highly loaded the pressure will be uniformly distributed in a controlled manner around the base ring and reinforcing wires, thereby reducing the tendency toward mechanical failure both of the elastomer and of the metal parts.

My invention will be readily understood by those 3,417,573 Patented Dec. 24, 1968 skilled in the art from the following description read together with the accompanying drawing, in which:

FIG. 1 is a half-sectioned elevation view of a preferred cup embodiment;

FIG. 2 is a similar View of this swab cup, associated with a cooperating mandrel assembly, and shown within Well-tubing or pipe;

FIG. 3 is a view similar to FIG. 2, but showing the cup heavily loaded;

FIGS. 4, 5, and 6 correspond respectively with FIGS. 1, ,2, and 3 but show a conventional swab cup lacking the present improved reinforcing ring; and

FIG. 7 is a perspective view of the reinforcing ring itself.

Proceeding now with a detailed description, in which like reference characters indicate similar parts among all the figures, the swab cups 1 shown in the drawing are intended to be mounted on a mandrel 10, similar to that set forth in my issued Patent 2,518,275, and having fluid passageway flutes 11. During downward travel of the assembly through the well fluid the swab cup 1 slides up along the mandrel 10 as shown in FIGS. 2 and until shoulder 12 of the swab cup 1 contacts shoulder 13 of mandrel 10. This positioning allows well fluids to by-pass the cup through flutes 11, and thereby permits the swab assembly to have a fast rate of fall. After the cup has reached a satisfactory depth in the well fluids, the ascent of the swab is begun, and the mandrel will move upwardly through the cup so that the seating face 16 of the metal base 14 comes into contact with seating face 15 of mandrel as shown in FIGS. 3 and 6. When this has been accomplished the downward load of fluid above the swab assembly causes the upper portion of the swab cup to distend radially outwardly into contact with the inner surface of the well pipe P, as illustrated in FIGS. 3 and 6. The well fluid, thus contained, is then lifted upwardly as the swab assembly is raised in the pipe by the operator. A fluid-tight seal between base 14 and surface is accomplished by the mating of the machined seating faces 15 and 16, together with the annulus 17 of resilient material within the swab cup, which is in sealing contact with the mandrel surface 9.

The metal base 14 has at its upper end an outwardly extending annular flange 18 which is provided with an annular series of holes 19 for receiving the lower ends of the individual reinforcing wires 20 which are booked as at 200. These reinforcing wires 20 are curved inwardly as at 20a at their upper ends to prevent snagging in the pipe joints, and the wires are relatively straight in their middle portions 20b to provide axially lengthy contact areas with the pipe walls. These wires are provided with hook portions 200 at their lower ends which curve radially inwardly, downwardly and then radially outwardly below the flange 18, thus creating a captivating hook lying in a radial plane of the swab cup.

As illustrated in FIGS. 2, 3, 5, and 6 this configuration permits each reinforcing wire 20 to be hooked into a flange hole 19 by tilting the wire radially outwardly as its hook is passed through the hole and then tilting the wire back toward vertical position. Resilient material, comprising the remainder of the cup assembly, is then molded and bonded by conventional techniques to form a known type of swab cup as illustrated in FIG. 4.

The conventional swab cup described to this point is improved according to the present invention by inserting an annular continuous cup-shaped rig 30, FIG. 7, into the elastomeric portion 5 of the cup just above the flange 18 and inside of the wires 20. The ring is preferably out of contact with the other metal parts and is bonded to the elastomeric material in a position which leaves a small amount of the resilient material between the ring 30 and the base 14 to act as a cushion therebetween, this cushion having the advantage of distributing pressures in the material above the ring more evenly against the wires 20 and flange 18. In such structures as this bending or pivoting of the wires must take place in order that the cup can expand to seal against the tubing along a significant axial length of the cup as viewed in FIGS. 3 and 6 when the cup is placed under heavy fluid load. The wires 20 can pivot outwardly around their hooked lower ends 205 to respond to light loads, but as the loading increases, the wires must distort to provide a greater axial-contact length with the well pipe P.

The wires are fairly close together so that the elastomer does not tend to bulge therebetween toward the pipe P under light loading, but under heavy loading as viewed in FIG. 6, the elastomer extrudes between and through the wires 20 to provide a bulge B of elastomer at the flange level, which bulge is then pinched and cut on edges of pipe joints until the elastomer is lost and the cup thereby weakened. Eventually the cup blows out and may even break away part of the flange 18 which is inherently weakened by the holes 19 which captivate the wire ends 200- On the other hand, it is desirable to let the elastorner expand freely into contact with the pipe P above the level where the portions 20b of the wires begin to contact the pipe when the cup is heavily loaded as shown in FIG. 3. Therefore the ring 30 should begin at and extend below this contact level, which has been marked K in FIG. 3. The reinforcement ring 30 is cup-shaped so that it approximates the inside contours of the wires 20 where they taper inwardly toward the hook portions 211C. Although the ring is separated from the wires 20 by thin intervening elastomeric material, the upper periphery of the ring 30 is disposed close enough to the wires so that the main bulk of the elastomer is radially inside the ring rather than between it and the wires.

For the sake of convenience of manufacture it is attractive to permit the ring 30 to lie on top of the metal base 14 near its inner sleeve portion 140 where the base is strong enough to support the ring so that any pressure exerted on the ring is carried by it and by the sleeve portion 14a, while the weaker flange portion 18 is protected therefrom and need only support the lower ends of the wires themselves which are no longer directly forced outwardly by the full pressure of the elastomer in which the lower ends are embedded.

However, this is not the most advantageous embodiment where the ring 30 lies on the metal base 14. Rather, it is better to have the lower periphery of the ring 30 spaced above the base 14 by a small thickness of elastomeric material. In either case, when the cup loading is increased the portions 20b of the wires just above the hooked ends 200 must expand outwardly to assume contact with the walls of the pipe P. When these portions of the wires move outwardly, the space vacated by the wires should be filled by downwardly-flowed elastomer. This elastomer can be supplied in correctly controlled quantity only if the ring 30 can move downwardly somewhat before being stopped by the base ring. By careful proportioning of the elastomer beneath the ring 30 and of the axial. increment through which the ring can move down before being stopped by the base 14, the amount of elastomer introduced into the zone vacated by the wires can be made adequate to insure freedom of the wires to move outwardly while at the same time preventing a large enough flow of elastomer into this region to cause the undesirable bulging which this invention is designed to cure.

The separation between the ring and the base and between the ring and the wires, in the relaxed condition of the cup, should be less than either the diameter of the wires or the spacing therebetween.

The present invention is not to be limited to the exact form shown in the drawing, for obviously changes may be made within the scope of the following claims.

I claim:

1. In a load-lifting swab cup having a flexible annular body extending in the direction of a longitudinal axis, the cup having a rigid base below said body and bonded thereto, and having wire members disposed longitudinally of the body and embedded in its outer surface and mutually spaced therearound, and the lower ends of the wire members being hooked and pivotally attached to said base, reinforcing means for uniformly distributing the load in the body near the base and for controlling the degree of extrusion of the body material outwardly between the wire members near the base comprising, a rigid annular ring separate from the base and embedded in free-floating relationship inside said flexible body radially within said wire members opposite their lower ends and spaced out of contact therewith, the ring having a lower periphery disposed just above said base and spaced out of contact therewith, and the ring being cup-shaped to approximately conform with the composite contour presented by the hooked lower ends of said wire members.

2. In a cup as set forth in claim 1, said base including an outwardly extending flange having an annular series of spaced axially-disposed holes therethrough, the hooked lower ends of said wire members extending downwardly 4 through the holes, and said cup-shaped ring tapering inwardly and downwardly, and its lower periphery terminating within the resilient body just above the base and radially inside of said annular series of holes.

3. In a cup as set forth in claim 1, the wire members each having a portion tapering inwardly toward their lower ends Where they are pivotally attached, and the ring being substantially axially coextensive with said inwardly tapering portion and being spaced from the wire members by a distance no greater than the mutual spacing therebetween.

4. In a cup as set forth in claim 1, the circumferential spacing between the wires approximating the diameter of a wire, and the ring being separated from the wires and from the base by distances smaller than said spacing.

References Cited UNITED STATES PATENTS 1,786,012 12/1930 Guiberson 92-241 2,352,812 7/1944 Taylor 92-241 2,466,572 4/ 1949 Bowerrnan 92241 2,609,258 9/1952 Taylor 92241 2,711,939 6/1955 Losey 92241 2,887,347 5/1959 Losey 92-241 2,013,903 9/1965 Thaheld 277181 X 2,305,282 12/1942 Taylor et al. 277181 X 2,965,422 12/1960 Wilson 277-481 MARTIN P. SCHWADRON, Primary Examiner.

GEORGE N. BAUM, Assistant Examiner.

US. Cl. X.R. 212-181, 212 

